Closure cap

ABSTRACT

A closure cap for openings on motor vehicle radiators is provided with a cap inner part that is held on a cap outer part. A valve assembly for opening and blocking a flow connection between the inside of the reservoir and the outside of the reservoir is held inside said cap inner part. The valve assembly comprises a valve body, which can move in a to-and-fro manner, is pressed in a pretensioned manner by spring action against a sealing seat on the cap inner part, and which can be lifted from the sealing seat when a specified limit value of the internal pressure of the reservoir is exceeded. The aim of the invention is to provide a closure cap of the aforementioned type whose sealing seat, which is located between the cap inner part and the valve body facing said cap inner part, undergoes a definable reduction of tension when the venting flow path is opened. To this end, the sealing seat on the cap inner part is formed by an O-ring, which is held inside an axially open annular groove, and this annular groove is radially enlarged by venting pockets provided on a circumferential edge.

The present invention relates to a closure cap for openings ofreservoirs, in particular motor vehicle radiators, as genericallydefined by the preamble to claim 1.

In one such closure cap, known from German Patent Disclosure DE 100 12184 A1, an O-ring is retained on the valve body in a radially open,asymmetrical groove; the O-ring presses against the annular edge face,embodied as a sealing seat, of the cap inner part and thus seals off aflow connection between the inside of the reservoir and the outside ofthe reservoir. If at a defined upper limit value of the internalreservoir pressure the spring force that presses the valve body againstthe sealing seat is overcome, the flow connection is opened. Since theregion of the O-ring located in the open, out of the asymmetrical radialannular groove, is located directly in the venting flow, there is a riskthat the O-ring will be forced out of its seat or out of the annulargroove by direct flow pressure and/or by venting flow turbulence. Thismeans that the vent opening will be delayed in coming into action and/orthat after the venting, the correct closure of the flow connection is nolonger assured.

The object of the present invention is therefore to create a closure capof the type defined at the outside, whose sealing seat, disposed betweenthe cap inner part and the valve body facing it, experiences a definedtension relief upon opening of the venting flow path.

In a closure cap of the aforementioned type, the characteristics recitedin claim 1 are provided for attaining this object.

By means of the provisions of the invention, it is attained that withthe lifting of the valve body and thus the opening of the venting flowconnection, the O-ring remains in the annular groove, since because theO-ring is ventilated from behind in the annular groove, a definedreduction of tension of the O-ring is attained, and the O-ring isprevented from sticking to the associated sealing face of the valvebody.

In a refinement of the invention, according to the characteristics ofclaim 2, the venting pockets are provided on the side of the O-ringremote from the flow passage between the valve body and the cap innerpart.

Further advantageous features of the venting pocket will become apparentfrom the characteristics of one or more of claims 3 through 5.

Further details of the invention can be learned from the ensuingdescription, in which the invention is described and explained infurther detail in terms of the exemplary embodiment shown in thedrawing. Shown are:

FIG. 1, in a longitudinal section, the cap inner part of a closure capfor a motor vehicle radiator with an overpressure/underpressure valveassembly, in a position after a limit value of the internal reservoirpressure is reached, in a preferred exemplary embodiment of the presentinvention; and

FIG. 2, a section taken along the line II-II in FIG. 1, but in theclosed outset position and with existing internal reservoir pressure.

The closure cap 11, for instance for a motor vehicle radiator, shown inthe drawing has, in a manner not shown, a cap outer part which isprovided with an actuating handle and on which a cap inner part 14 withan underpressure/overpressure valve assembly 15 is retained. In theposition for use, the closure cap 11 is affixed to or screwed onto aradiator neck, not shown. The cap inner part 14 protrudes inside theradiator neck in the direction of the radiator interior. An O-ring 16 onthe outside, represented by dot-dashed lines, seals off the cap innerpart 14 from the radiator neck wall. The overpressure part of the valveassembly 15 is embodied with two stages and serves in a firstoverpressure stage to prevent the radiator from boiling dry, and in asecond overpressure stage, security against damage to the radiatorsystem from excessive overpressure is assured.

The overpressure part of the valve body 15, in the interior of the capinner part 14, has a first valve body 17, a second valve body 18, and athird valve body 19. The first valve body 17 is disposed above thesecond valve body 18 in the direction toward the outside of the cap,while the third valve body 19 is received coaxially inside the secondvalve body 18.

The first valve body 17 is embodied like a valve plate standing on itshead; an annular seal 21 provided with an axially inward-orientedsealing face is mounted on the side of the plate toward the radiatorinterior. The first valve body 17 is acted upon, from a side facing awayfrom the radiator interior, by a closing compression spring 22represented only by dot-dashed lines, which is braced on its other endindirectly on the cap inner part 14 in a manner not shown. By means ofthe closing compression spring 22, the first valve body 17 isprestressed in the direction of the radiator interior. Via the seal 21,embodied as a flat sealing ring, the first valve body 17 is seated on afirst annular sealing seat 24 of the second valve body 18. The one-piecesecond valve body 18 has a hood part 26, which on its free end isprovided with the first sealing seat 24, and a receiving part 27 for thethird valve body 19, which part is concentric and hollow-cylindrical andpoints from the bottom 28 of the hood part 26 toward the radiatorinterior. The bottom 28 between the hood part 26 and the receiving part27 is provided on the outer circumference with a collar, whose underside29 forms a second sealing seat relative to the cap inner part 14.Associated with this second sealing seat 28 is an inner O-ring 31, whichis received in an annular groove 30 that is disposed in a collar edge 32of the cap inner part 14 in such a way that it is open axially upward(toward the bottom 28 of the second valve body 18). The collar edge 32is embodied between a hollow-cylindrical upper region, of the cap innerpart 14 of larger inside diameter and receiving both the first valvebody 17 and the hood part 26 of the second valve body 18, and a lowerregion of the cap inner part 14, of smaller inside diameter, surroundingthe receiving part 27 of the second valve body 18. In this lower region,the cap inner part 14 is provided with an axial opening 33 for flowconnection with the inside of the reservoir. In the outset state, notshown in FIG. 1, the first valve body 17 is pressed with its first ringseal 21 against the first sealing seat 24 of the second valve body 18 bythe closing compression spring 22, and the second valve body is in turnpressed with its second sealing seat against the second ring seal(O-ring 31) on the cap inner part 14.

The annular groove 30, open axially upward, in the collar edge 32 of thecap inner part 14 is provided with venting pockets 35, which are formedby slots 36 that originate at the larger-diameter inner circumferentialedge of the annular groove 30. The slots 36 extend over the entire axialdepth of the annular groove 30. The slots 36 or venting pockets aredistributed uniformly in a large number (in this case 16) over thecircumference of the annular groove 30 (FIG. 2). FIG. 1 shows a flowconnection 40, made when the second valve body 18 has lifted from theO-ring 31, from the inside of the reservoir to the outside of thereservoir between the inner edge of the collar edge 32 and the lower capinner part region, and between the second sealing seat 28 and the O-ring31. FIG. 2 also shows the location of the O-ring 31 in the annulargroove 30 when the venting path 40 is closed, that is, in a position inwhich the second valve body 18 rests with its second sealing seat 28 onthe O-ring 31 in the cap inner part 14 by the action of the closingcompression spring 22. In this closing position, which seals off theflow connection or venting path 40 in pressuretight fashion, the O-ring31 is compressed by the disposition of the venting pockets 35 and bulgesradially outward in undulating fashion in the region of these ventingpockets. That is, upon opening of the venting path 40 under theinfluence of an internal reservoir pressure that exceeds the applicablelimit value, a defined reduction of tension of the O-ring 31 can beeffected; as a result, the O-ring 31 cannot lift axially but insteadremains inside the annular groove 30 in every case.

The following can be said about the operating conditions in the closurecap 11. In the outset operating position, not shown, the first valvebody 17 is seated on the second valve body 18 (as in FIG. 1), and unlikewhat is shown in FIG. 1, the second valve body 18 rests on the cap innerpart 14 or on the O-ring 31. If a first limit value of the internalreservoir pressure is exceeded, the first valve body 17 is liftedcounter to its closing compression spring 22, since a communicationexists between the inside of the reservoir and the underside of thefirst valve body 17, past the tightly closing third valve body 19 andthrough the second valve body 18. As a result of opening of a first flowconnection, air from the air cushion located above the liquid radiatormedium can flow outward and as a result can compensate for theoverpressure or eliminate it. The second valve body 18 remains pressedin sealing fashion against the collar edge 32 of the cap inner part 14.If the so-called overpressure is reduced again to below the first limitvalue, then the first valve body 17 comes back into sealing contact withthe second valve body 18. Conversely, if the internal reservoir pressureincreases further even during or after the escape of the air cushion,the result is that liquid radiator medium reaches the underside of thesecond and third valve bodies 18 and 19, and in a manner explained forthe prior art recited at the outset, a ram pressure results, leading toan axial motion of the third valve body 19 counter to its thirdcompression spring 43; as a result of this sealing motion of the thirdvalve body 19, the first flow connection mentioned is closed. Reducingthe pressure leads again to a reverse motion of the third valve body 19and opening of this connection path, after which the first flowconnection mentioned is closed again. Conversely, if the internalreservoir pressure continues to increase, then if an upper safetypressure limit value is exceeded, the second valve body 18 will liftfrom the O-ring 31 of the cap inner part 14, counter to the firstclosing compression spring 22 bearing on the first valve body 17, sothat the so-called second flow connection 40 is opened, and theaforementioned very high overpressure can be reduced (see FIG. 1).

For the sake of completeness, it should also be noted that FIG. 1 alsoshows an underpressure valve body 57 inside the first overpressure valvebody 17.

It is understood that the number of venting pockets shown in FIG. 2 mayalso be less or greater, and that the venting pockets may also bedisposed in an irregular arrangement along the circumference of theannular groove. It is furthermore possible for the venting pockets to beprovided not on the larger-diameter inside circumference of the annulargroove but on the smaller-diameter circumference of the annular groove,radially inward. In an exemplary embodiment not shown, the ventingpockets are formed by conically extended or stepped slots.

1-5. (canceled)
 6. A closure cap for a reservoir opening having: a capouter part; a cap inner part, retained on said cap outer part, said capinner part defines a sealing seat and an axially open annular groove;and a valve assembly situated in said cap inner part, for opening andblocking a flow connection between the inside of the reservoir and theoutside of the reservoir, said valve assembly having a valve bodymovable back and forth and which is resiliently prestressed, and pressedagainst said sealing seat and which can be lifted from said sealing seatif a defined limit value of the internal reservoir pressure is exceeded,wherein: said sealing seat is formed by an O-ring retained in saidaxially open annular groove, and said annular groove is radially widenedby venting pockets provided on a circumferential edge of said annulargroove.
 7. The closure cap according to claim 6, wherein: said ventingpockets radially adjoin the outer circumferential edge of said annulargroove.
 8. The closure cap according to claim 6, wherein: said ventingpockets extend over the entire depth of said annular groove.
 9. Theclosure cap according to claim 6, wherein: said venting pockets aredistributed uniformly over the circumference of said annular groove. 10.The closure cap according to claim 6, wherein: said venting pockets areformed by narrow radial slots.
 11. The closure cap according to claim 7,wherein: said venting pockets extend over the entire depth of saidannular groove.
 12. The closure cap according to claim 7, wherein: saidventing pockets are distributed uniformly over the circumference of saidannular groove.
 13. The closure cap according to claim 8, wherein: saidventing pockets are distributed uniformly over the circumference of saidannular groove.
 14. The closure cap according to claim 7, wherein: saidventing pockets are formed by narrow radial slots.
 15. The closure capaccording to claim 8, wherein: said venting pockets are formed by narrowradial slots.
 16. The closure cap according to claim 9, wherein: saidventing pockets are formed by narrow radial slots.